In a steam trap of a double seated valve known from WO 2012/168221 A2, the closure body comprises, subsequent to the conical sealing face, a cylindrical extension which, at the open position as well as at the closed position, engages a hollow-cylindrical extension of the seat and delimits therein a circular passage. The size of the passage remains unchanged during displacements of the closure element and limits a predetermined flow rate. The closure element is adapted to be displaced up to and into full shut-off contact with the seat. At the open position of the seat valve, the cleaning medium is discharged. At the closed position, the steam pressure is maintained until the seat valve is, depending on the respective temperature, displaced to the open position so as to discharge the accruing condensate. The steam trap is connected to a lower shut-off valve of a valve chamber of a double seated valve, said valve chamber being cleaned and sterilized with sterile steam. The condensate resulting from the application of steam is here discharged at the open position of the seat valve, which, depending on the prevailing temperature, is maintained at the fully sealing, closed position as long as no condensate occurs.
In a steam trap, which is known from WO 2015/039724 A1 and which is connected to a condensate line that branches off from a piping arrangement of a processing system, the closure element arranged upstream of the seat, when seen in the direction of discharge, is adapted to be displaced by means of a thermodynamic actuator and/or a pneumatic actuating means relative to the seat between a sealing closed position, a throttling partially closed position and a fully open position.
DE 4036581 A1 discloses a steam trap, which, via a switchover valve, is connected to the discharge valve of a double seated valve. The switchover valve opens, during the flushing cycle, a path having a large cross-section and leading to the outlet, while the steam trap is isolated.
U.S. Pat. No. 5,628,339 A discloses a steam trap connected to the steam line of a hot-water boiler and comprising a passage in a valve screw insert.
DE 1711575 U discloses a steam trap for steam heatings, in the case of which a closure element having a frustoconical shape or the shape of a circular cylinder is provided with grooves in the circumferential surface, said grooves defining constant cross-sections without any jet effect in the direction of discharge.
It is the object of the present disclosure to provide a steam trap, an aseptic double seated valve, a method of operating the steam trap and a filling plant, which are reliable in function, cost-efficient and which require little maintenance, with the steam trap comprising the least possible number of components and allowing a reduction of the constructional outlay in an aseptic double seated valve.
At the closed position, a jetlike passage is kept open in the steam trap by the closure element and the seat, so that the steam trap operates according to the advantageous principle of a jet-type steam trap. Accruing condensate is permanently discharged via the passage, while the steam pressure is largely maintained. This is important for the efficiency of the sterilization cycle. At the open position, the seat valve opens a large cross-section, which corresponds to the passage of the drain valve and which, in the first discharge state, allows the large throughput of condensate and product residues. The large throughput as well as the small throughput are discharged via the same path, so that it is no longer necessary to provide a conventional switchover valve and the piping required thereof, which discharges only the small throughput into the steam trap, but which, bypassing the steam trap, discharges the large throughput into the outlet. The passage, which, in the discharge direction, is first narrow and increases in width subsequently and which acts as a diffusor from the physical point of view, generates a counterpressure due to the evaporation of the superheated condensate and the expansion of the resultant steam, said counterpressure controlling the amount of condensate flowing through and, consequently, the steam pressure on the sterilization side is maintained almost constant. Cold condensate, which accumulated in the system, is discharged more quickly via the passage, since the latter is effective without the re-evaporation effect. The space required for the steam trap and for installing the latter on the aseptic double seated valve is reduced. The steam trap consists of a small number of components and, in view of said small number of components, it is cost-efficient and requires little maintenance, since, when in operation, it will be self-cleaning. When the large throughput is discharged via the seat valve at the open position, the then exposed passage will be cleaned reliably, whereby a clogged passage will be avoided at the closed position. If the passage should tend to clog during the sterilization cycle, it will be possible to carry out automated cleaning via a control by temporarily displacing the closure element to the open position or in the direction of the open position, so that deposits on the components of the passage will be flushed away. The steam trap is extremely robust and hard-wearing. The use of seals acted upon by pressure can be dispensed with, since shaft seals that may possibly be provided on the actuator only have to seal off an almost pressureless rear space. Due to the simple structural design of the steam trap, servicing of the latter will easily be possible at any time.
In the case of the aseptic double seated valve provided with the steam trap, the large throughput of condensate and product residues will, during a flushing cycle, be conducted to the outlet via the same path in the steam trap as the small throughput of condensate resulting from the steam applied, so that a normally provided switchover valve with complex piping will no longer be necessary and the aseptic double seated valve will require little maintenance due to effective self-cleaning of the seat valve in the steam trap.
According to an expedient embodiment of the steam trap, the sealing face and the seating area either have identical cone top angles, or the sealing face has a very small width and is increased in width as a receding area through a subsequent smaller cone top angle, whereby a gap increasing in width is formed between the sealing face and the seating area. In the first case, a large-area contact region is created at the closed position, in which the contour for the passage is incorporated either in the seating area or in the sealing face. In the second case, the contact created is substantially a line contact, interrupted by the contour of the passage. The passage area which increases in width subsequent to the constriction is here defined by the sealing face and the seating area which open at an acute angle.
According to an expedient embodiment, the seat increases in width from the intake side in the discharge direction so as to form a valve chamber leading to the outlet. The closure element is adapted to be moved, on a linear actuator extending through the valve chamber, relative to the seat to the open position into the valve chamber and to the closed position out of the valve chamber and into the seat. In this way, the flow-through resistance is extremely low at the open position of the seat valve, as is desirable for the large throughput. The closure element is, however, moved to the closed position against the flow in the discharge direction, whereby the path can be narrowed gradually, with the exception of the passage that allows a flow to pass. The linear actuator is driven e.g. pneumatically, electrically or electromagnetically. The cone top angle of the seat is an angle of approximately 30° to 60°, and in one embodiment, an angle of approximately 40°. These angles allow the flow to expand freely into the valve chamber in the case of a large throughput.
According to the embodiment having differing cone top angles, these cone top angles should differ by approximately 1° to 10°. This is the angular difference with which the passage increases in width from the constriction onwards.
The axial length of the sealing face and/or the seating area may correspond to approximately 50% of the smallest seat diameter. Thus, the passage has an optimum great length that may be advantageous with respect to good flow conditions.
According to an expedient embodiment with differing cone top angles, the constriction may be created by a cylindrical milled-out portion in the area of the seat, which is easy to produce from the point of view of production technology and which can also easily be measured. The milled-out portion extends at the intake side over part of the height of the seating area and the sealing face. The area increasing in width from the constriction onwards is defined by the angular difference between the sealing face and the seating area.
According to an embodiment having identical cone top angles, however, the passage extends over the entire height of the sealing face and/or the seating area. When seen in the discharge direction, the passage begins with a cylindrical portion and increases in width conically subsequent to said cylindrical portion.
A reduction of width at the inlet of the passage can be dispensed with in the case of both embodiments, since the fluidic efficiency of the passage is not of importance.
It is definitely possible to provide a plurality of milled-out portions in the circumferential direction.
According to the embodiment in which parts of the passage are arranged in an approximately mirror-inverted manner in the seating area as well as in the sealing face, these parts are oriented relative to one another as a pair in the circumferential direction. To this end, the closure element may be protected against rotation relative to the seat.
According to an expedient embodiment, the linear actuator is a piston rod of a piston, which is adapted to be acted upon by pressurized fluid against the force of a spring, said piston rod being displaceable such that it is sealed off from the valve chamber. The piston is here may be acted upon by a spring force in the direction of adjustment of the seat valve to the open position, so that the seat valve will maintain the open position without any application of pressurized fluid to the piston. At the state of rest, the steam trap is so to speak in a standby condition ready for the large throughput. The closed position is only adjusted, e.g. by applying pressurized air, when a sterilization cycle is initiated. The closure element may alternatively be displaced in both directions by means of a linear drive. When the flushing cycle with large throughput is carried out, the parts of the passage will always be flushed and efficiently cleaned. If the passage should clog during a sterilization cycle at the closed position, this can be detected by means of a temperature detector, which e.g. detects the temperature at the intake side or in a leakage chamber of the double seated valve or in the vicinity of the steam trap. Subsequently, the seat valve may be transferred to the open position at least once more, so that the clogged passage will be cleaned by backed-up condensate which will then flow off rapidly and dynamically.
In the case of the aseptic double seated valve, it will be expedient when an intake side or the housing and/or the discharge path to the seat valve of the steam trap are provided with at least one installed temperature detector, which, acting as a temperature measuring unit, detects the temperature conditions in this area, so that it will then also be possible to switch the seat valve between the open and closed positions in a temperature-dependent manner.
One embodiment of the aseptic double seated valve has a leakage chamber in the housing, said leakage chamber having connected thereto the check valve and the drain valve for the purpose of flushing with condensate and sterilizing with steam. Possibly existing product residues are flushed away from the leakage chamber via the steam trap with large throughput, prior to executing subsequently a sterilization cycle with steam, during which the seat valve is at the closed position, but accruing condensate is discharged with small throughput via the passage that allows a flow to pass.
In the sense of a carry over part philosophy, which allows the use of many identical parts and seals, the check valve, the drain valve and the seat valve of the steam trap may, at least substantially, be identical in construction.
The concept of the steam trap allows the latter to be installed e.g. in a filling plant at a double seated valve either with a substantially horizontal valve axis or a substantially vertical valve axis, e.g. in adaptation to the respective installation space available.